In drilling wells for water or oil, a rotary bit is typically powered from above the surface by a suitable rotary drill head. The bit is carried on the lower end of a drill string comprised of a number of pipe sections that are joined together, usually by threaded engagement. A mud slurry is typically pumped downwardly through the drill string in order to carry cuttings from the drill bit upwardly around the pipe surface and out of the drill hole.
Frequently, drill rigs of this type are mounted on trucks or tracked vehicles so that they may be driven to the drill site. Such vehicles typically have a drilling mast that is pivotally mounted on the vehicle chassis so that it may be pivoted from a generally horizontal travel position to a generally vertical drilling position. The drill head is mounted on the mast and is adapted to rotate the drill string as it pushes it downwardly. Because it may be necessary to drill to a depth of hundreds or thousands of feet, the length of the drill string must be increased as drilling proceeds. Each time the drill head reaches the lower end of the mast, it must be disconnected from the drill string and raised to the upper end of the mast so that another drill pipe may be added to the drill string. Generally, a plurality of individual drill pipes, each of which may be twenty feet long, are stored in a pipe storage magazine on or near the drill rig, and a pipe handling assembly is provided to transfer drill pipes from the storage magazine to the drill string. After drilling is completed, the pipe handling assembly is employed to take the drill pipes from the drill string, one by one, and replace them in the storage magazine.
Pipe handling assemblies are described in the following U.S. Pat. No. 3,145,786, No. 3,734,209, No. 4,403,897, No. 4,547,110, No. 4,604,724, No. 4,708,581, No. 4,834,604, No. 4,951,759, No. 5,931,238, No. 6,220,807, No. 6,298,927, No. 6,311,788 and No. 7,469,749, as well as in U.S. patent application publications No. 2007/0031215 and No. 2007/0092358.
Some drill pipe handling systems for use in transferring drill pipes between a storage device and a drill head operate by raising one side of the support surface of a storage device so that drill pipes will roll towards or away from a drill pipe receiver mounted on a pipe gripping arm. Such systems are described and illustrated in U.S. Pat. No. 4,547,110, No. 4,604,724, No. 4,951,759, No. 6,311,788 and No. 7,469,749, and in U.S. patent application publications No. 2007/0031215 and No. 2007/0092358. Other drill pipe handling systems operate by moving a drill pipe transfer mechanism between a generally vertical drilling position and a generally horizontal pipe transfer position. Thus, for example, U.S. Pat. No. 6,298,927 (“the '927 patent”) describes a pipe storage and handling system for a drilling rig which includes a pipe control arm assembly that is adapted to move individual drill pipe sections between a horizontal storage rack and a drill head for the vertical drill string. The pipe storage rack is adapted to store pipe sections in three vertical columns. A pipe lifting assembly is provided with an indexing mechanism that includes an indexing cylinder and a pipe saddle assembly. The pipe saddle assembly is adapted to engage the lowermost drill pipe section in the middle column of the pipe storage magazine, so that as the rod of the indexing cylinder is extended, the middle pipe column is raised until the uppermost drill pipe section is positioned in a selection location from which it can be grabbed by the control arm assembly. Then, the rod of the indexing cylinder is extended by an amount equal to the diameter of a pipe section to move another pipe section in the middle column of the magazine into the selection location. This process is repeated until all of the pipe sections are removed from the middle column. A pipe shifting assembly is then employed to shift one of the other pipe columns to the middle column position, so that the pipe sections in this second column can be removed in the same manner as those in the first. Thereafter the shifting assembly is employed to shift the third pipe column to align it with the indexing axis, so that the pipe sections in the third column can be removed. One disadvantage of the assembly of the '927 patent is that it must always remove a drill pipe from the center column in the storage magazine. If fewer than all of the drill pipes in the storage magazine are used, this system will not allow the drill operator to cycle through all of the drill pipes, thereby causing them to wear unequally.
Notes on Construction
The use of the terms “a”, “an”, “the” and similar terms in the context of describing the invention are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising”, “having”, “including” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The terms “substantially”, “generally” and other words of degree are relative modifiers intended to indicate permissible variation from the characteristic so modified. The use of such terms in describing a physical or functional characteristic of the invention is not intended to limit such characteristic to the absolute value which the term modifies, but rather to provide an approximation of the value of such physical or functional characteristic.
The steps of any method described herein in connection with the preferred embodiments of the invention can be performed in any suitable order unless otherwise indicated herein, explicitly or by context. The use of any and all examples or exemplary language (e.g., “such as”) herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. Nothing in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Various terms are specifically defined herein. These terms are to be given their broadest possible construction consistent with such definitions, as follows:
As used herein, the term “drill pipe” and similar terms refer to elongate tubes or rods that are used in the drilling or boring of wells and other openings into the earth. “Drill pipes” are commonly, but not necessarily, tubular. They are generally adapted to be joined together, usually by threaded engagement, to form a drill string that carries a drill head. Those having ordinary skill in the art to which the invention relates may use the term “drill pipes” synonymously with the terms drill rods, well casing, production tubing and similar terms:
As used herein, the term “linear actuator” and similar terms refer to an electric, hydraulic or electro-hydraulic device that generates force which is directed in a straight line. One common example of a “linear actuator” is a hydraulic cylinder which includes a cylinder, a piston within the cylinder, and a rod attached to the piston. By increasing the pressure within the cylinder on one side of the piston (over that on the opposite side of the piston), the rod will extend from the cylinder or retract into the cylinder.